The De litteris, de syllabis, de metris presents its arguments in the order that is canonical to the grammatical artes (letters, syllables, meters), but it stands apart for its complex treatment of the subject — it was certainly intended for those who already possessed some knowledge of the material — as much as for its facies, because its verses draw it closer in essence to the genre of the didactic poem. The text was rediscovered in Bobbio in 1493 (cfr. infra); it is incomplete, due to damage (probably from mechanical failure) to the manuscript, and consists of almost 3,000 verses in various meters, mainly hexameters and trochaic tetrameters. The work is structured in the following manner (this concise outline is based on the Cignolo edition, pp. XXXI-XXXVII, which may be consulted for a more detailed analysis):

Praefatio (vv. 1-84), in continuous glyconic meter.

De litteris (vv. 85-278, sotadic meter): elementa; a description of the articulation of sounds; letters as numerical symbols; coda.

De syllabis (vv. 279-1299): introduction; the letters; the syllables; characteristics of prosody; coda. At v. 999, the catalectic trochaic tetrameters are replaced by hexameters: this section specifically addresses meter and prosody, and draws its examples exclusively from Vergil. The book is dedicated to Terentianus’ son Bassinus and his son-in-law Novatus, who were charged for correcting and polishing the text and seeing to its publication.

De metris (vv. 1300-2981): This section begins with an introduction concerning vowels and syllables and a treatment de pedibus; then Terentianus plunges into the main discussion of meter (vv. 1580ss.: a characterisation of meters; mixed meters), in the middle of which is the incomplete passage on Horatian meters. Following the theory of derivatio metrorum, two meters are examined, which are considered more ancient and of the same origin: dactylic hexameter (the heroicus) and the iambic meter — that is, trimeter — and the meters that could derive from them. Vergil is placed side by side with the authors Terentianus uses as models: Catullus, Horace, and the poetae novelli: this variety of exempla is reflected in his list of diverse metra (trochaic and iambic verses, hexameter, lyric verses).

The work’s internal elements contain evidence that the three books possess reciprocal autonomy, which suggests that this did not originate as one single text: there are literal repetitions between one section and another, and there is a circumscription between the programmatic tone of an incipit and an epilogue in De syllabis, where Terentianus himself refers to this section as a single work (v. 348: hoc opus de syllabis). This hypothesis is strengthened by later authors’ citations, which always refer to single books of the treatise, thereby attesting — in all probability — that the three sections circulated separately.

Numerous possibilities are currently being evaluated concerning the work’s date, the relationship between the three books, and between the books and the praefatio. Perhaps De metris was Terentianus’ last composition, and published posthumously (Sallmann), or maybe, on the contrary, it predated the other two books (Beck). Maybe the praefatio was originally an introduction to De syllabis alone (Schanz-Hosius, Wessner, Castorina); the most recent editor suggests that the three were distinct texts, but that perhaps their author united them in a single corpus for publication. She proposes a probable order in which they were composed: that De metris was written first, considering Terentianus’ specific poetic interests; then De litteris, as a detailed study on letters; lastly, De syllabis, completing the work; the traditional order would then have been preferred, when preparing the work for publication, since it was “based on the logical development of the treatise and conforms to the canons of the grammatical tradition” (Cignolo XLI).

Terentianus’ use of sources is an object of ongoing study, but his attitude is distinct in reference to his arguments. Far from the philosophical elements that are typical in the Greek tradition (the sophists, Plato), Terentianus’ analysis in De litteris is simply technical, and reveals a strong dependence on the De compositione verborum of Dionysius of Halicarnassus, probably read through a Latin text that is unknown to us. It is already easy to presume Varro’s presence in this section (he is explicitly mentioned in De metris), and the possibility that Terentianus also used the Dubii sermonis libri of the Elder Pliny must be carefully considered (consider that he mentions Plinius v. 863, in the book on syllables: Strzelecki). Although the treatises conform to the structure of grammatical manuals, De syllabis presents assertions and analyses that are not attested elsewhere; as yet these lack comparanda, but they allow us to conjecture on the knowledge and transmission of theories outside the world of the school. De metris, through its interest in prosody, again suggests an indirect connection to the work of Dionysius of Halicarnassus: the presentation of the meters attests to a clear adherence to the theory of derivatio metrorum; according to tradition, this theory had already spread to Rome through Varro in the first century BCE, and in any case, it was the basis of Caesius Bassus’s treatise De metris in the early imperial period.

Terentianus Maurus’ treatise was certainly known and used until the end of the 6th/7th century; it was rediscovered in 1493, together with other grammatical and metrical texts (Caesius Bassus, Atilius Fortunatius, anonymous excerpta): these were part of the famous discovery of codices in Bobbio by Giorgio Galbiate, the secretary of the humanist Giorgio Merula (Ferrari, Morelli, Cignolo). The codex was badly damaged, but it was copied by Galbiate himself, who then obtained the privilege of publishing it: the editio princeps of De litteris, de syllabis, de metris is dated to 1497 (this is the only text, of those preserved in the manuscript from Bobbio, that Galbiate printed). Since the manuscript is now lost, this edition must be accepted as the ancestor of an almost entirely print tradition.

In 1504, the humanist Giano Parrasio curated another edition (preceded in 1503 by the typographer Giovanni da Cerreto), while in 1508 Aldo Manuzio published numerous excerpts of the treatise within the Institutionum Grammaticarum libri quattuor. Among the numerous editions of Terentianus, we draw attention to Brisseo’s Paris edition (1531), which was the first to be accompanied by a commentary, and especially to the 1532 edition of Moltzer (the Micillus), who is responsible for dividing the work into three parts. Among the modern editions, we highlight those of van Santen (1825), Lachmann (1836; this edition rehabilitates the text of the princeps against that, then widespread, of Brissaeus), and Gaisford (1855); naturally we must recall that of Keil, who incorporated Terentianus Maurus’ treatise into the corpus of the Grammatici Latini (1874), for the most part reproducing Lachmann’s text. In 1993, Beck published De syllabis, with a lengthy critical apparatus and commentary. The most recent editor, Chiara Cignolo, established the text on the basis of the princeps, but also considered the text of the 17th-century codex Matritensis 4248 (M. 229), which was pointed out by Gaisford and consists of an unpublished edition with notes prepared by Juan Vázquez del Mármol. The notes that the Ferrarese humanist Celio Calcagnini made on his copy of the editio princeps are also interesting, as they constitute the earliest exegetical work on Terentianus’ text; his copy is now at the Biblioteca Ariostea di Ferrara (Cignolo, Per la storia del testo). [Anita di Stefano; tr. C. Belanger]